The present invention relates to a support structure for supporting the push button mounted to the actuator of the push switch for turning on and off the indoor room lithts such as a light attached to the center of the roof of the automotive room, the map lamp forwardly of the driver's seat or the like to prevent the push button from listing at the time when said switch is pressed down for turning on and are again pressed down for turning off the lights.
One example of the map lamps for automotive indoor illumination used in the prior art will be explained with reference to FIGS. 7 through 9.
A housing 1 to which a lamp (not shown) is attached has a transparent or translucent lens 2 secured thereto at a front thereof. Said housing 1 has a push switch 3 (hereinafter referred to as merely a switch) for turning on and off said lamp and said switch is secured to a platform 11 formed integrally to one side of said housing 1. Said switch 3 has an actuator 31 which are to be engaged with a push button 4 and is adapted to be operated from the front of the housing. On the underside of the push button 4, a cylindrical rod 41 is integrally formed thereto to be inserted into a cylindrical bearing 12 integrally formed to the platform 11.
The terminal (not shown) of the thus constructed switch 3 is electrically connected to the power source (or the automotive battery) and is adapted to turn on the switch 3 to put on the light by being pressed down and to turn off the same to put out the light by again being pressed down again.
Since the rod 41 is guided along said bearing 12 therewithin, the button is prevented from listing sideways at the time of the push button 4 being pressed down to ensure that said push button 4 is vertically pressed down to in turn press down the actuator 31 positively to assure a proper switching on and off actions.
In this connection, said push button having rods 41 being inserted into the bearing 12 which is tubular provides a large contact area between the rods 41 and the bearing 12. This structure gives a rise to a considerable frictional resistance when pressing down the push button 4, thus preventing a smooth pressing down of the same.
Further, the prior art as described in the foregoing employs cylindrical rods 41 and tubular bearings 12, which can prevent smooth pressing down of the push button if the outer diameter of the rods 41 and the inner diameter of the bearings 12 are substantially equal because it provides too tight engagement while if the difference between said outer diameter and said inner diameter are too large, an unnecessary play can cause a resultant deflection of the push button at the time of the pressing down action.